STERICALLY STABILIZED LIPOSOME THERAPEUTICS

Biotechnology, based on the concept of natural macromolecules as therapeutic agents while successful has been thwarted by a need for in vivo delivery. Sterically stabilized liposomes, ones modified at the surface with hydrophilic polymers (PEG), have proven to reduce in vivo recognition and phagocytic uptake, resulting in prolonged circulation and localization in tumors as well as other sites of pathology. This has restored their potential as a widely useful delivery system but also has created new challenges: the need to keep the agent associated with the liposome during circulation and distribution followed by control of its release for activity. Several specific drug formulations have been developed which are described along with some of the important parameters for their consideration in order to be considered for other agents. Finally, the value and issues surrounding future expansion are discussed: targeting and cell delivery for gene therapy.